From the year 1300 the Cara traditions gather more clearness and precision. By a law handed down from immemorial times each Shiri was succeeded by his son, or if he had no son by the son of a sister, daughters and other female descendants being absolutely excluded. The eleventh Shiri, whose reign corresponded with the last years of the thirteenth century, had no male heir, and he asked the general council of the nation for permission to name as successor the husband he might choose for his daughter. Each one of the different chiefs, hoping to be selected, voted for the proposition, but the Shiri diplomatically went outside of his own dominions and proposed to the monarch who ruled in Riobamba that his eldest son, Duchisela, marry the Princess Toa. The proposition was accepted and the Quito kingdom doubled its territory and power.
Duchisela reigned seventy years, and upon his death was succeeded by his son Autachi, the thirteenth Shiri. This monarch raised the Cara power to its highest pitch, extending his dominions south over the plateaux of Alausi, Cañar, Cuenca, Jubones, Zaruma, and Loja, and thence far beyond the present Ecuadorian boundary over the Peruvian provinces of Huanacabamba, Piura, and Paita. This vast increase of territory was due more to treaties of confederation and alliance than to conquest. None of the new provinces were ever thoroughly incorporated into the Cara confederacy, and their allegiance to the Shiri in far-away Quito sat lightly upon them. By the end of the fourteenth century the Cara influence was dominant along the Andean plateau from the first degree of north latitude to the sixth south, and extended to the arid coast plain of northern Peru. The humid and forested coast region north of Guayaquil remained in the hands of barbarous tribes, nor were the Caras ever able to extend their power down the wooded eastern slopes of the Andes into the Amazon plain.
Cara expansion was suddenly checked by the Incas. In the latter part of the fourteenth century these fierce and indomitable Islamites of the western continent under the lead of Tupac Yupanqui conquered the coast nations from Lima to Paita, and the ruder tribes who lived in the mountains from Cerro de Pasco north to the Ecuadorian border. Tupac did not respect the southern confederates of the Caras, and the Shiri appears to have made little resistance when his allies were rapidly reduced. The Inca system was the far better adapted for conquest. The emperor could equip and lead to invasion armies numbering tens of thousands, well disciplined, blindly obeying their generals, marching over carefully prepared roads, and supplied by an admirable commissariat. The Caras had contented themselves with treaties of alliance; they were only the chief tribe in a confederacy, and warlike as were the members they could not combine to offer any effective resistance to the first onslaught of the great military empire.